I'm going base model, adding 4gb Crucial Ram, and a 5.4k 500GB Scorpio Blue HDD from Newegg. The 5.4k 500GB was rated faster than the 7.2k drive, I've heard because the disk is higher density. Also it gets better battery performance!
I have a thread on the new macbook HDD
here.
I have a feeling you might shoot me after this post but I have an update
I went back this morning to make sure I wasn't letting online reviews and 'logic' talk me into getting the little guy. This time I specifically went in to check screen quality and physical size including the MBA in my decision. I had talked (thought) myself out of the MBA but my heart still wants that machine.
I took the 4 machines into a back room (my 17" Applecare story has become the in store joke at this point so they're letting me get away with being very anal). I did two tests this time. One was the same as before - web page and word document and the second was the same picture in iPhoto, full screen, zoomed in all the way.
The 13" looked a little washed out when compared to the 15" screen. Maybe not by much but I could notice it. The 17" is in a league of its own. When compared to the 13" MBP the new MBA still seemed much much better. Noticeably so.
I'm very torn/confused AGAIN at this point. At first I was set on the 15". But the very slight increase in portability (its still quite big/heavy) doesn't justify the dramatic drop in the screen resolution. Yesterday, before I did my second subjective visual test at the Store in a darm rook, I had convinced myself to go with the 13" MBP. Figured if I was dropping resolution and had to get used to a smaller work space, I may as well get some real portability and get used to the 13" screen.
Now .. I can't live with the screen on the 13" MBP. Resolution I have no choice but the actual screen is a step down from both the 15" and the MBA.
The 13" MBP is still a chunky heavy machine and I'm coming from a 17" aircraft carrier. If you're going to go 'small and portable' the MBA is it. The little MBP just did_not_do_it for me. There's also a slight elitist thing. (may as well be honest here). I don't want the cheap machine everyone has now that the price is affordable. I do want something different / 'pro' to set me apart. The 17" MBP has the fantastic screen and the bragging rights of being the lightest, thinnest desktop replacement. The 13/15 MBPs are just ... meh.
I played with the new MBA with SSD. That's the one I want and lust after but I don't think its a smart move to buy it right now. I do like the glass trackpad on the others and given the red headed step child treatment, I think its close to being EOLed.
Honestly, I think I'm going to skip this round of updates and see what's next. I *like* them but don't need them and the one that I want - MBA - I'm nervous about buying. The specs are pretty low as well.
I'm pretty sure I can squeeze another year out of my trusty workhorse. (It's a joke at the store because when I went in to pick it up the inventory list of repairs said - Screen, Screen Bezel, Keyboard, Top case, Bottom Case, Both fans and the logic board!!! What's left??

)
Maybe I should have kept quiet instead of confusing myself and everyone else in this thread buuut ... wanted to be honest and help anyone trying to make a similar decision ...
Cheers,
eV